Ironic that you are talking about unrepresentative samples while characterizing Reddit users that way. Reddit is a huge subsection of the internet, over a billion monthly active users. It covers basically all strata of western society you can think of.
They seem to count unregistered users in the D/W/MAU, but even so the producer / consumer of content ratio across social media still stands. What you read is a subsection of all visitors to Reddit, which follows the power law.